1. Field of the Invention
The present invention concerns offshore platforms in which the supporting substructure or jacket is fabricated remote from the site of platform installation. More particularly, the invention concerns method and apparatus for connecting two sections of an offshore jacket for an offshore platform in water at a shore location remote from the deep water installation site at which the offshore platform is to be erected.
2. Description of the Prior Art
It is known in the art that offshore platforms may be installed in deep waters by floating the platform jacket in a horizontal position to the site for installation of the offshore platform in an assembled or an unassembled condition. At the installation site the legs of the jacket are controllably flooded to cause the jacket to assume an upright position on the sea floor.
In U.S. Pat. No. 3,859,806, entitled "Offshore Platform" filed Oct. 1, l973 by Guy et al., a method for fabricating an offshore platform for use in deep water is disclosed in which sections of the platform support component or jacket are connected together while the sections are floating in a horizontal position in the water. The sections are guided into proper alignment and then joined. Access tubes from the surface of the water to the legs of the sections permit direct internal welding in securing the legs of the sections together. The sections are then floated to a selected erection site and the sections sunk at that site by controllably flooding the legs until the jacket is in an upright position. The jacket is then anchored to the sea floor by driving pilings through the jacket's hollow legs into the sea floor. Thereafter the deck of the platform is placed or stabbed on the anchored jacket.
The present invention involves erecting an offshore platform in deep water in the manner described in the aforementioned Guy et al patent; however, instead of connecting sections of the jacket while they are floating in the water at least one of the jacket sections is first grounded in a stationary position at a shore or beach site. This invention is applicable where no protected water is available or where ambient sea conditions are too rough to connect sections of the jacket together while they are floating.